The lowermost Upper Devonian fossil Pallaviciniites was for a time the oldest known liverwort until Metzgeriothallus was recovered from earlier Devonian strata.[2]

It had a central axis, and bifurcated at its tips; similar fossils have been found in younger strata through to the Pleistocene.[3] With the exception of its elongated axial conducting (non-vascular) cells, the thallus was a single cell thick.[4] It had a serrated margin.[1]

Prior to its discovery, the oldest known liverworts dated to the Lower Carboniferous.[3]